Membrane bioreactor systems have been utilized on-board commercial vessels to treat influent waste such as wastewater derived from various sources so as to: (a) eliminate perturbations in flow and temperature, (b) reduce biochemical oxygen demand, (c) reduce total suspended contaminating solids and (d) reduce fecal coliform concentration. Such systems involve collection of raw, non-oily wastewater fed into a tank for processing by membrane filtration and biological treatment to induce growth of the aerobic bacteria therein, promoted by aeration and carbon dissolved in the wastewater embodied in the solids carried therein. The wastewater so processed is withdrawn with reductions in biological oxygen demand, total suspended solids, and fecal coliform concentrations.
The maximum organic and hydraulic load capability of such bioreactor systems is limited by size of bioreactor tanks, concentration of contaminating solids within the wastewater being processed and the number of membranes through which permeate filtration is performed. While performing filtration on wastewater with or near the maximum allowable solids concentration therein, in a bioreactor system having a reduced size for shipboard installation, fouling of the membranes associated therewith increases so as to limit their operational life and require frequent cleaning and/or replacement. It is therefore an important object of the present invention to reduce temporary and permanent fouling of the membranes associated with such bioreactor systems so as to provide a more viable processing method, especially on-board sea vessels having limited installation space.